HP spare part: Display back cover, Ambient light sensor (includes cable). Unverified source; not bench-tested.
Source notes
Manual on file for HP Elite c640 14 inch G3 Chromebook Maintenance and Service Guide, PDF page 21: "Ambient light sensor (includes cable) N13938-001". Source link not recorded and not verified as an HP document (red, not sure). (via v10 fold 2026-11-12)